This invention relates to a rotodynamic fluid machine which can perform useful work on a fluid as a pump or compressor or which can derive useful work from a fluid as a fluid motor.
In one form the invention resides in a rotodynamic fluid machine comprising a plurality of separate co-axial cylindrical chambers, each chamber having a drive rotor mounted therein, the drive rotors being fixedly mounted on a common shaft to provide a drive rotor assembly, each rotor having a plurality of spiral blades formed thereon, the blades on the respective rotors being arranged so that if the rotors were to be placed in end-to-end abutting relationship the blades would be contiguous with the contiguous blades having an angle of wrap exceeding 360/n where n is the number of blades on each drive rotor so that neighbouring contiguous blades overlap in the longitudinal direction of the rotor axis, each drive rotor mating with a pair of sealing rotors located in lateral chambers positioned parallel to the cylindrical chamber and intersecting the cylindrical chamber, said sealing rotors being fixedly mounted on respective common shafts to provide respective sealing rotor assemblies, said sealing rotors being provided with spiral recesses to receive the spiral blades of the driving rotors to provide continuous meshing engagement between the drive rotor assembly and each sealing rotor assembly, each said central chamber being divided into two working chambers by the drive rotor and the two sealing rotors therein, the two working chambers being disposed one to each side of the line of centres of the drive rotor and the two sealing rotors, each working chamber having an inlet port and an outlet port circumferentially spaced from the inlet port.
There is at all times one drive rotor of the drive rotor assembly in meshing engagement with its mating sealing rotors of the sealing rotor assemblies. This ensures that the drive rotor assembly and two sealing rotor assemblies remain in synchronisation.
Preferably, said inlet and outlet ports of each working chamber extend substantially the full axial length of the working chamber.
Preferably, said inlet port for each working chamber is located adjacent to the pitch point between one sealing rotor and the drive rotor, and the outlet port is located adjacent to the pitch point between the other sealing rotor and the drive rotor.